This invention relates to an adaptive array antenna receiving apparatus, in particular, to an adaptive array antenna receiving apparatus for performing RAKE combining of a desired signal came through a plurality of paths (or a multi-path).
A code division multiple access (CDMA) system attracts attention as a radio transmitting system capable of considerably increasing a subscriber capacity. For example, a CDMA adaptive array antenna receiving apparatus used in the CDMVA system is disclosed in Wang et al xe2x80x9cAdaptive Array Antenna Combined with Tapped Delay Line Using Processing Gain for Direct-Sequence/Spread-Spectrum Multiple Access Systemxe2x80x9d (IEICE Transactions, Vol. J75-BII, No. 11, pp. 815-825, 1992) and Tanaka et al xe2x80x9cThe Performance of Decision-Directed Coherent Adaptive Diversity in DS-CDMA Reverse Linkxe2x80x9d (IEICE, Technical Report on Radio Communication System, RCS96-102, November 1996). As disclosed in these articles, antenna weights are controlled by the use of a weighting control error signal derived after despreading. In this manner, adaptive control is carried out so that an antenna directive pattern maximizing a received SIR (Signal to Interference Ratio) is formed to cancel an interference.
However, the CDMA adaptive array antenna receiving apparatus has a problem that it takes a long time to be converged antenna weights.
It is therefore an object of this invention to provide an adaptive array antenna receiving apparatus capable of shortening a convergence time of antenna weights.
Other object of this invention will become clear as the description proceeds.
According to an aspect of this inventions an adaptive array antenna receiving apparatus forms a beam for each path of a multipath. The adaptive array antenna receiving apparatus comprises an existing state detecting unit(s) to detect an existing state regarding existing fingers. An antenna weight succession processing unit is connected to the existing state detecting unit(s) and selects one of the existing fingers on the basis of the existing state. The antenna weight succession processing unit borrows antenna weights used for the selected existing finger to provide the borrowed antenna weights for a newly assigned finger or another one of the existing fingers that a path timing is changed.
According to another aspect of this invention, an adaptive array antenna receiving apparatus has a plurality of receiving antennas for receiving signals to produce received signals. A plurality of signal processing units processes assigned fingers corresponding to paths of a multipath for a desired signal. The signal processing units includes antenna weight adaptive controllers to individually control antenna weights used for weighting the received signals. The adaptive array antenna receiving apparatus comprises an existing state detecting unit(s) to detect an existing state regarding existing fingers. An antenna weight succession processing unit is connected to the existing state detecting unit(s) and the antenna weight adaptive controllers and selects one of the existing fingers on the basis of the existing state as a selected finger. The antenna weight succession processing unit extracts antenna weights from one of the antenna weight adaptive controllers that corresponds to the selected finger. The antenna weight succession processing unit supplies the extracted antenna weights as initial antenna weights for another one of the antenna weight adaptive controllers that corresponds to a newly assigned finger or to another one of the existing fingers that a path timing is changed.
According to still another aspect of this invention, a method is used in an adaptive array antenna receiving apparatus. The adaptive array antenna receiving apparatus has a plurality of receiving antennas for receiving signals to produce received signals. A plurality of signal processing units is for existing fingers corresponding to paths of a multipath for a desired signal. The signal processing units include antenna weight adaptive controllers to individually control antenna weights used for weighting the received signals. The method is for providing initial antenna weights for a newly assigned finger or a path timing changed finger. The method comprises the steps of detecting an existing state of the existing fingers, selecting one of the existing fingers as a selected finger on the basis of the existing state, extracting the antenna weights from one of the signal processing units that corresponds to the selected finger, and providing the extracted antenna weights to the newly existing finger or the path timing changed finger.